U.S. patent application number 09/912406 was filed with the patent office on 2002-04-25 for monitoring and controlling ink pressurization in a modular ink delivery system for an inkjet printer.
Invention is credited to Barinaga, John A., Gasvoda, Eric L., Lewis, Richard H., Monclus, Antoni, Puchal, Xavier Gasso.
Application Number | 20020047881 09/912406 |
Document ID | / |
Family ID | 27499998 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020047881 |
Kind Code |
A1 |
Lewis, Richard H. ; et
al. |
April 25, 2002 |
Monitoring and controlling ink pressurization in a modular ink
delivery system for an inkjet printer
Abstract
An air pressurization system is incorporated as part of a
replaceable auxiliary ink supply for an inkjet printer The
auxiliary ink supply cartridge includes a pressurized container
having air, ink and electrical signal connections. The air pressure
applied to the auxiliary ink supply is monitored to be maintained
in a predetermined range in accordance with a start-up sequence, an
operational sequence, a waiting time, and a close-down
sequence.
Inventors: |
Lewis, Richard H.;
(Barcelona, ES) ; Gasvoda, Eric L.; (Salem,
OR) ; Puchal, Xavier Gasso; (Barcelona, ES) ;
Monclus, Antoni; (Barcelona, ES) ; Barinaga, John
A.; (Portland, OR) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P. O. Box 272400
Fort Collins
CO
80528-9599
US
|
Family ID: |
27499998 |
Appl. No.: |
09/912406 |
Filed: |
July 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09912406 |
Jul 24, 2001 |
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09495666 |
Feb 1, 2000 |
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6290343 |
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09495666 |
Feb 1, 2000 |
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08988018 |
Dec 10, 1997 |
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6030074 |
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08988018 |
Dec 10, 1997 |
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08679579 |
Jul 15, 1996 |
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08988018 |
Dec 10, 1997 |
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09240039 |
Jan 29, 1999 |
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6206512 |
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08988018 |
Dec 10, 1997 |
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08871566 |
Jun 4, 1997 |
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6074042 |
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Current U.S.
Class: |
347/85 |
Current CPC
Class: |
B41J 2/17509 20130101;
B41J 2/17553 20130101; B41J 2/17523 20130101; B41J 2/17556
20130101; B41J 2/17513 20130101; B41J 2/17503 20130101; B41J 2/175
20130101 |
Class at
Publication: |
347/85 |
International
Class: |
B41J 002/175 |
Claims
We claim as our invention:
1. A system for ink replenishment for an inkjet printer comprising:
a frame for holding one or more ink supplies; an interconnect
member on said fame, said interconnect having an ink supply
interface and an air supply interface; an air compressor device in
communication with said air supply interface to provide air to an
ink supply module to facilitate transmission of liquid ink from
said ink supply module to an inkjet print cartridge; a sensor for
monitoring the air pressure of said air compressor device; and
control electronics coupled to said air compresssor device and to
said sensor to activate said air compressor device based on signals
received from said sensor.
2. The system of claim 1 which further includes an ink supply
module having liquid ink therein.
3. A method of providing ink from an auxiliary ink supply to an
inkjet printhead, comprising: providing an auxiliary supply of ink
in a collapsible bag inside of a protective enclosure; connecting
the auxiliary ink supply with a print cartridge through an ink
delivery conduit; subjecting the collapsible bag to air pressure
greater than ambient air pressure to facilitate transmission of the
ink to the print cartridge; monitoring the air pressure of said
subjecting step; and controlling the operation of an air compressor
in order to maintain the air pressure in accordance with
predetermined parameters.
Description
FIELD OF INVENTION
[0001] The present invention generally relates to print cartridges
used in computer controlled printers, and more particularly, to
methods and apparatus for delivering ink to such print
cartridges.
BACKGROUND OF INVENTION
[0002] One problem in ink-jet printing is that some applications
require a large supply of ink. For example, "large format"
applications use large size printing media (for example, 22
inch.times.34 inch. 34 inch.times.44). Examples of large format
applications include computer aided design (engineering drawings),
mapping, graphic arts, and posters. The large format printed image
can use a large amount of ink either because of the large printed
area needing to be covered with ink or the use of 100 percent
filled-in image areas, or both. Therefore, it is desirable to have
ink reservoirs that contain a large amount of ink to avoid
replacing an empty ink reservoir in the middle of a printing cycle
or the frequent changing of the ink reservoir between printing
jobs.
[0003] However, merely increasing the size of the ink reservoir in
an on-board system to hold more ink has not proved to be an
acceptable solution. The ink reservoir is supported on the printer
carriage and moves with the printhead. Increasing the amount of ink
in motion would necessarily require an increase in the size and
weight of the structure that supports and moves the carriage back
and forth. The increased mass of the carriage would also
significantly increase the cost of the printer (for example, larger
and more expensive electrical motors).
[0004] In response, recently, relatively large ink reservoir
systems have developed in which the reservoir is mounted
off-board.
[0005] In contrast to on-board ink reservoirs, printing systems
using off-board reservoirs require means for delivering the ink
from the off-board ink reservoir to the printhead. Pumps can be
used for such delivery, but such pumps have problems associated
with their use. For example, the ingredients in the ink can be
incompatible with the pump components, and such components as
diaphragms and seals can degrade when exposed to the ink solvents
for extended time periods.
[0006] A second problem in ink-jet ink delivery arises in color
printing. Color printing typically uses multiple ink reservoirs,
each containing ink of a different hue. Since each ink reservoir
must be individually pressurized, multiple pumps can be used.
However, the addition of each additional pump increases the cost of
the overall printing system. Thus, it would be desirable to use one
pump that can provide the necessary pressure for all the ink
reservoirs individually.
[0007] One other problem in ink-jet technology is that customers
have different purchasing criteria. Some customers, with high ink
usage rate, may prefer the lower "unit price" of a large ink
reservoir. Other customers, may prefer a lower, "start-up" price of
a smaller ink reservoir. Thus, it would be beneficial for the
customers to have a printing system that is adaptable to ink
reservoirs with different sizes. In addition, the manufacturer also
benefits when the size of the ink reservoir is not a limiting
factor in the design of the printer or the ink delivery system.
SUMMARY OF THE INVENTION
[0008] Briefly and in general terms, an apparatus for delivering
pressurized ink to a printhead, according to the invention,
includes a deformable bag for holding ink, a pressurizable
container substantially surrounding the bag for exerting fluid
pressure on said bag and pressurizing any ink within the bag, and a
sealable ink outlet port for fluid communication with the ink bag.
The port is fluidically connectable to the printhead so that
pressurized ink is deliverable to the printhead.
[0009] The invention contemplates a process having the steps of:
providing a deformable bag for holding ink for a printhead;
substantially surrounding the bag with a pressurizable container;
exerting fluid pressure on the bag by pressurizing the container,
thereby pressurizing any ink within the bag; and delivering
pressurized ink to the printhead.
[0010] In a presently preferred embodiment of the invention, the
air pressure system is incorporated as part of a replaceable
auxiliary ink supply as well as part of a replaceable ink delivery
system having air, ink and electric signal connections to the
auxiliary ink supply. The ink pressure applied to the auxiliary ink
supply is monitored to be maintained in a predetermined range in
accordance with a start-up sequence, an operational sequence, a
waiting time, and a close-down sequence.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is a perspective view, partially in section and
partially cut away, of an apparatus for delivering pressurized ink
to a printhead embodying the principles of the present
invention.
[0012] FIG. 1B is a perspedtive view, partially in section and
partially cut away, of a second embodiment of the present invention
showing a pressurized fluid in fluid communication with a
pressurizable container.
[0013] FIG. 2A is an isometric exploded view of a fluid connection
between a pressurizable container and a quick ink disconnect
valve.
[0014] FIG. 2B is an isometric, exploded view of a fluid connection
between the pressurizable container and a quick air disconnect
valve.
[0015] FIG. 3 depicts a schematic representation of a printing
system that includes an ink container of the present invention.
[0016] FIG. 4A depicts a perspective view of a leading edge portion
of the ink container; FIG. 4B depicts a side view thereof; and FIG.
4C depicts a plan view, partially broken away, of the electrical
connection portion thereof.
[0017] FIG. 5A depicts a perspective view of an ink container
receiving station shown partially broken away with an ink container
installed; FIG. 5B depicts a cross-section taken across line 5B-5B
of the ink container receiving station shown partially broken
away.
[0018] FIG. 6A is a perspective view of a large format printer
incorporating the present invention; FIG. 6B is a top plan view
thereof with its cover removed to show the printhead carriage and
ink tube guides and supports.
[0019] FIG. 7A is a front elevation view of the printhead
connector, partly broken away, with a printhead carriage being
shown in phantom; FIG. 7B is a top plan view thereof showing
printhead lockouts therein with portions of the printhead carriage
shown in phantom.
[0020] FIG. 8 is a perspective view from below of a printhead
showing a lockout tab configuration which mates with the cyan color
slot of the printhead connector.
[0021] FIG. 9 is a front elevation view of the reservoir connector
with one reservoir lockout removed.
[0022] FIG. 10 is a perspective of a lockout receivable in the
reservoir connector having a fin configuration complementary with
the fin configuration on an ink reservoir.
[0023] FIG. 11 is an elevation of the ink connection end of an ink
reservoir having a fin configuration complementary with the fin
configuration of the reservoir connector lockout of FIG. 10.
[0024] FIG. 12 is a rear elevation view of the reservoir
connector.
[0025] FIG. 13 is a left side elevation view of the reservoir
connectior, the right side view being a mirror image thereof.
[0026] FIG. 14 is a top plan view of the reservoir connector.
[0027] FIG. 15 is a vertical cross section of the reservoir
connector showing a connector module resiliently mounted
therein.
[0028] FIG. 16 is a top perspective view of a support member
holding an air pump, pressure sensor and pressur relief valve.
[0029] FIG. 17 is a schematic diagram of the air pressure
system.
[0030] FIGS. 18A through 18D depict a flow diagram showing a
presently preferred operational sequence for the air pressure
system.
[0031] FIG. 19 shows an exemplaryl duty cycle for the air pressure
system.
[0032] FIG. 20 shows a side-by-side comparison of a 350 cc and a
700 cc ink reservoir.
[0033] FIG. 21 shows a schematic view of a tower on the reservoir
connector with the humidor and ink need removed.
[0034] FIG. 22 shows a schematic view of a humidor with an ink
needle shown inside.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Referring to FIG. reference numeral 10 generally indicates a
pressurizable container for exerting fluid pressure on a deformable
ink bag 13 which contains a liquid ink 16.
[0036] The container 10 is an air impermeable rigid container which
houses the ink bag 13. The container 10 is attached to a chassis 19
to form a hermetic seal. A method for securing such a seal is to
choose the same material, such as HDPE (high density polyethylene),
for both the chassis 19 and the container 10 and to use an
attachment process such as ultrasonic welding, or heat staking, or
adhesive bonding. A gas inlet port 55 allows pressurized air 73 to
flow into the container 10.
[0037] The ink bag 13 is constructed from a multi-layer metallized
polymer film, such as metallized PET (polyethylene terephthalate),
with a sealant layer made of LDPE (low density polyethylene). The
bag 13 has a high barrier property to water diffusion and other
solvents present in the ink 16. The ink bag 13 can be of any shape
and size suitable for holding the ink 16. The ink bag 13 is
flexible, deformable, and collapses when its contents are
emptied.
[0038] The ink bag 13 is heat staked onto an external surface 21 of
a fin 22 to make a hermetic, fluid tight seal. Also, the fin 22 is
attached to the chassis 19 to form a hermetic, fluid tight seal. A
method for making the fin to chassis seal is to choose the same
material, such as HDPE (high density polyethylene), for both the
chassis 19 and the fin 22 and to use an attachment process such as
ultrasonic welding, or heat staking, or adhesive bonding. In the
preferred embodiment the fin 22 has a diamond shape for
manufacturing ease. The fin 22 has two ports, an ink inlet port 28
and an ink outlet port 31. The fin 22 is connected to a first ink
conduit 34 at the ink outlet port 31. The first ink conduit has a
sealable outlet port 25 and is connected to a second ink conduit 42
by a first male connector 37. The sealable ink outlet port 25
[0039] The first male connector 37 is located on a base 46 of a
printer 49. The first ink conduit 34 and the second ink conduit 42
are made of a material with high barrier property, such as FEP
(fluorinated ethylene propylene), to diffusion of air and ink
solvents (including water). The ink 16 is in fluid communication
with a print cartridge 44 via the bag 13, the fin 22, the first ink
conduit 34 and the second ink conduit 42.
[0040] Referring to FIG. reference numeral 44 generally indicates
the print cartridge connected to the second ink conduit 42. The
print cartridge also includes a printhead 40. The print cartridge
is of conventional thermal ink-jet construction and operation. The
print cartridge 44 also includes a pressure regulator 41 for a
preset back pressure (for example, minus 2 inches of water)
required for the printhead 40 to function. When the pressure inside
the printhead 40 is lower than atmospheric pressure, a condition
exists that is called back pressure (or negative pressure). Back
pressure is necessary to keep ink from drooling out of the nozzles
(not shown here) of the printhead 40. The pressure regulator 41 is
in fluid communication with the ink 16 in the second ink conduit 42
on one side, and the printhead 40 on the other side. Depending on
the pressure inside the printhead 40, the pressure regulator 41
allows or stops the flow of the ink 16 to the printhead 40.
[0041] Further referring to FIG. the container 10 is in fluid
communication with a first gas conduit 56 having a sealable gas
inlet port 52 and the gas inlet port 55. The gas inlet port 55 is
received in the container 10. The first gas conduit 56 is connected
to a second gas conduit 64. The second gas conduit has a second
male connector 58 that is insertable into the sealable gas inlet
port 52. The sealable gas inlet port 52 and the second male
connector 58 together, make a second quick disconnect valve 67. See
FIG. 2B. The second male connector 58 is located on the base 46 of
the printer 49.
[0042] The container 10, the ink bag 13, the fin 22, the chassis
19, the first ink conduit 34, the first gas conduit 56, the
sealable ink outlet port 25, and the sealable gas inlet port 52 are
collectively referred to as an ink containment device 11.
[0043] Referring to FIG. reference numeral 61 generally indicates
an air manifold. The air manifold 61 contains a first gas outlet
port 70 for providing air 73 to the container 10 via the second gas
conduit 64. The number of the first gas outlet ports 70 on the
manifold is a matter of design to accommodate all the pressurizable
containers 10 that house the ink bags 13. Only one container and
ink bag is illustrated in FIG. 1 avoid redundancy. In a typical
color ink-jet printing device there are four ink reservoirs: black,
magenta, cyan, and yellow. Thus, on such a color printer the air
manifold 61 has four first gas outlet ports 70. An air compressor
76 is electrically connected to the printer 49 so that the
compressor 76 is turned on when the printer 49 signals the air
compressor. The air compressor 76 has a second gas outlet port 82
which is connected to an air chamber 85 in the air manifold 61 via
a third gas conduit 88. The air compressor 76 can be any
commercially available unit capable of providing air at a pressure
of about 2 psi and at an air flow rate of about 150 cc/min.
[0044] The air manifold 61 has an air bleed vent 90 for providing a
continuous bleed. The bleed vent is a commercially available ball
92 and spring 93. The purpose of the continuous bleed is to
minimize the exposure of the seals in the system to an elevated
pressure when the printer is not in operation and second, to
equilibrate the system's pressure and to avoid over pressurization
during operation. When the pressure inside the air chamber 85
exceeds the desired pressure of 2 psi, the ball 92 compresses the
spring 93 to allow excess air to exit through the air bleed vent
90.
[0045] Referring to FIG. in operation, the first male connector 37
and the second male connector 58 are inserted into the sealable ink
outlet port 25 and the sealable gas inlet port 52, respectively.
These insertions bring the ink containment device 11 in fluid
[0046] When the air compressor 76 is turned on, the air 73 flows in
turn through the second gas outlet port 82, the third gas conduit
88 and into the air chamber 85. The air 73 is then directed to the
first gas outlet port 70 and thereafter through the second gas
conduit 64, the second quick disconnect valve 67, the first gas
conduit 56, the gas inlet port 55 and into the container 10.
[0047] The pressure of the air inside the container 10 exerts a
pressure on the ink bag 13 containing the ink 16. This pressure
causes the ink 16 to flow through the ink inlet port 28 and
thereafter through the fin 22, the ink outlet port 31, the first
ink conduit 34, the first quick disconnect valve 43, the second ink
conduit 42 and into the pressure regulator 41.
[0048] As the ink is jetted out of the printhead 40, the pressure
inside the print head 40 decreases until it reaches a preset back
pressure. The difference between the back pressure on one side of
the pressure regulator 41, in communication with the printhead 40,
and the more positive causes the pressure regulator 41 to open and
to allow the ink 16 to flow into the printhead 40. When the
pressure in the printhead 40 reaches the preset operating pressure,
the flow of ink stops and the differential pressure across the
pressure regulator is equilibrated.
[0049] FIG. 3 illustrates embodiment of the present invention. For
the two embodiments like reference numerals indicate like
components. In referring to FIG. reference numeral 10' generally
indicates a pressurizable container for exerting pressure on the
deformable ink bag 13 which contains the liquid ink 16. A sealable
fluid inlet 12, such as a septum, is located in a sidewall 15 of
the container 10' for receiving a pressurized fluid 22 such as air.
A pressurized fluid cylinder 18 holds the pressurized fluid 22. The
pressurized fluid 22 is in fluid communication with the container
10 through a pressure regulator 31, a fluid conduit 25, and a
hollow is commercially available and is set for a pressure of about
2 psi. The fluid conduit 25 is made of any material that can
support an air pressure of about 2 psi.
[0050] Referring to FIG., in operation, the hollow needle 28 is
inserted into the septum 12. The pressurized fluid cylinder 18 is
opened and the pressurized fluid 22 moves through the pressure
regulator 31, the fluid conduit 25, the needle 28, and into the
container 10. The needle 28 can remain in the septum during normal
operation. Upon inserting the first male connector 37 into the
sealable ink outlet port 25, the system is ready for operation in
the same manner as described above in connection with FIG.
[0051] It should be appreciated that: any pressurizable fluid,
including a liquid, that is compatible with the pressurization
system can be used in place of the air 73 and the fluid 22; the fin
22 has a diamond shape but any other shape that can accommodate the
ink bag 13 and the chassis 19 can be used; the preset back pressure
is minus 2 inches of water but the pressurization system described
here can accommodate any other back pressure requirements that the
printhead 40 may have; only one type of air compressor 76 is
described but any type of pump capable of providing the desired air
pressure and flow rate may be used such as those pumps used in fish
aquariums; and the desired pressure in the ink conduits, the gas
conduits, and the containers 10 and 10' is 2 psi but pressures in
the range from minus 10" of water to over 45 psi can be used.
[0052] FIG. depicts a schematic representation of a printing system
10 ink container 12 of the present invention. Also included in the
printing device 10 is a printhead 14 and a source of pressurized
gas such as a pump 16. The pump 16 is connected by a conduit 18 for
providing a pressurized gas such as air to the ink container 12. A
marking fluid 19 such as ink is provided by the ink container 12 to
the printhead 14 by a conduit 20. This marking fluid is ejected
from the printhead 14 to accomplish printing.
[0053] The ink container 12 which is the subject of the present
invention includes a fluid reservoir 22 for containing ink 19, an
outer shell 24, and a chassis 26. In the preferred embodiment the
chassis 26 includes a air inlet 28 configured for connection to
conduit 18 for pressurizing the outer shell 24 with air. A fluid
outlet 30 is also included in the chassis 26. The fluid outlet 30
is configured for connection to the conduit 20 for providing a
fluid connection between the fluid reservoir 22 and fluid conduit
20.
[0054] In the preferred embodiment the fluid reservoir 22 is formed
from a flexible material such that pressurization of the outer
shell produces a pressurized flow of ink from the fluid reservoir
22 through the conduit 20 to the printhead 14. The use of a
pressurized source of ink in the fluid reservoir 22 allows for a
relatively high fluid flow rates from the fluid reservoir 22 to the
printhead 14. The use of high flow rates or high rates of ink
delivery to the printhead make it possible for high throughput
printing by the printing system 10.
[0055] The ink container 12 also includes a plurality of electrical
contacts, as will be discussed in more detail with respect to FIG.
The electrical contacts provide electrical connection between the
ink container 12 and printer control electronics 32. The printhead
control electronics 32 controls various printing system 10
functions such as, but not limited to, printhead 14 activation to
dispense ink and activation of pump 16 to pressurize the ink
container 12. In one preferred embodiment the ink container 12
includes an information storage device 34 and an ink level sensing
device 36. The information storage device 34 provides information
to the printer control electronics 32 for controlling printer 10
parameters such as ink container 12 volume as well as ink
characteristics, to name a few. The ink level sense device 36
provides information relating to current ink volume in the ink
container 12 to the printer control electronics 32.
[0056] As ink 19 in each ink container 12 is exhausted the ink
container 12 is replaced with a new ink container 12 containing a
new supply of ink. In addition, the ink container 12 may be removed
from the printer chassis 38 for reasons other than an out of ink
condition such as changing inks for an application requiring
different ink properties or for use on different media. It is
important that the ink container 12 be not only accessible within
the printing system 10 but also easily replaceable. It is also
important that the replacement ink container 12 form reliable
electrical connection with corresponding electrical contacts
associated with the printer chassis 38 as well as properly form
necessary interconnects such as fluid interconnect, air
interconnect and mechanical interconnect so that the printing
system 10 performs reliably. The present invention is directed to a
method and apparatus for reliably engaging the ink container 12
into the printer chassis 38 to insure proper electrical
interconnection is formed.
[0057] It is important that ink spillage and spattering be
minimized to provide reliable interconnection between the ink
container 12 and printer 10. Ink spillage is objectionable not only
for the operator of the printer who must handle the spattered ink
container 12 but also from a printer reliability standpoint. Inks
used in ink-jet printing frequently contain chemicals such as
surfactants which if exposed to printer components can effect the
reliability of these printer components. Therefore, ink spillage
inside the printer can reduce the reliability of printer components
thereby reducing the reliability of the printer.
[0058] FIGS. 3 and 4 depict the ink container 12 of the present
invention. The ink container 12 includes a housing or outer shell
24 which contains the fluid reservoir 22 shown in FIG. 1 for
containing ink 19. The outer shell 24 has a leading edge 50 and
trailing edge 52 relative to a direction of insertion for the ink
container 12 into the printer chassis 38. The leading edge 50
includes the air inlet 28 and the fluid outlet 30 which are
configured for connection to the air pump 16 and the printhead 14,
respectively, once the ink container 12 is properly inserted into
the printer chassis 38. The air inlet 28 and fluid outlet 30 will
be discussed in more detail
[0059] A plurality of electrical contacts 54 are disposed on the
leading edge 50 for providing electrical connection between the ink
container 12 and printer control electronics 32. In one preferred
embodiment the plurality of electrical contacts 54 include a first
plurality of electrical interconnects that are electrically
interconnected to the information storage device 34 and a second
plurality of electrical interconnects which are electrically
interconnected to the ink volume sensor 36 shown in FIG. 1. In the
preferred embodiment the information storage device 34 is a
semiconductor memory and the ink volume sensing device 36 is an
inductive sensing device. The electrical contacts 54 will be
discussed in more detail with respect to FIG.
[0060] The ink container 12 includes one or more keying and guiding
features 58 and 60 disposed toward the leading edge 50 of the ink
container 12. The keying and guiding features 58 and 60 work in
conjunction with corresponding keying and guiding features on the
printer chassis 38 to assist in aligning and guiding the ink
container 12 during insertion of the ink container 12 into the
printer chassis 38. The keying and aligning features 58 and 60 in
addition to providing a guiding function also provide a keying
function to insure only ink containers 12 having proper ink
parameters such as proper color and ink type are inserted into a
given slot printer chassis 38. Keying and guiding features are
discussed in more detail in co-pending patent application Ser. No.
08/566,521 filed Dec. 4, 1995 entitled "Keying System for Ink
Supply Containers" assigned to the assignee of the present
invention and incorporated herein by reference.
[0061] A latch feature 62 is provided toward the trailing edge 52
of the ink container 12. The latch feature 62 works in conjunction
with corresponding latching features on the printer portion to
secure the ink container 12 within the printer chassis 38 such that
proper interconnects such as pressurized air, fluidic and
electrical are accomplished in a reliable manner. The latching
feature 62 is a molded tang which extends downwardly relative to a
gravitational frame of reference. The ink container 12 shown in
FIG. 4 positioned for insertion into a printer chassis 38 along the
Z-axis of coordinate system 64. In this orientation gravitational
forces act on the ink container 12 along the Y-axis.
[0062] FIG. depicts an electrical interconnect portion 70 which is
the subject of the present invention. The electrical interconnect
portion 70 includes electrical contacts 54 and upstanding guide
member 72, and inner wall member 74, and an outer wall member 76.
In the preferred embodiment, the plurality of electrical contacts
54 include electrical contacts 78 which are electrically connected
to the fluid sensing device 36 shown in FIG. and electrical
contacts 80 which are electrically connected to the information
storage device 34. In the preferred embodiment, the electrical
contacts 78 are defined in a flexible circuit 82 which is mounted
to the ink container 12 by fastener 84. A circuit 86 on which
contacts 80 and information storage device 34 are disposed provides
electrical connection between the information storage device 34 and
contacts 80. The circuit 86 is attached to the ink container 12 by
fastener 84.
[0063] The inner upstanding wall 74 and the outer upstanding wall
76 help protect the electrical circuit 86, information storage
device 34, and contacts 78 and 80 from mechanical damage. In
addition, the upstanding walls 74 and 76 help minimize inadvertent
finger contact with the electrical contact 78 and 80. Finger
contact with the electrical contact 78 and 80 can result in the
contamination of these electrical contacts which can result in
reliability problems with the electrical connection between the ink
container 12 and the printing system 10. Finally, inadvertent
contact with the electrical contact 78 and 80 can result in an
electrostatic discharge (ESD) which can result in reliability
problems with the information storage device 34. If the information
storage device is particularly sensitive to electrostatic discharge
such a discharge may result in catastrophic failure of the
information storage device 34.
[0064] FIG. depicts an ink container 12 of the present of the
present invention shown secured within an ink container receiving
station 88 within the printer chassis 38. Because ink container 12
is similar except for keying and guiding features 58 and 60 and
corresponding ink properties contained within the respected fluid
reservoir, the same reference numbering will be used for each ink
container 12. An ink container indicia 90 may be positioned
proximate each slot in the ink container receiving station 88. The
ink container indicia 90 may be a color swatch or text indicating
ink color to assist the user in color matching for inserting the
ink container 12 in the proper slot within the ink container
receiving station 88. As discussed previously the keying and
guiding features 58 and 60 shown in FIGS. prevent ink containers
from being installed in the wrong slot. Installation of an ink
container in the wrong slot can result in improper color mixing or
the mixing of inks of different ink types each of which can result
in poor print quality.
[0065] Each receiving slot within the ink container receiving
station includes a corresponding keying and guiding slot 92 and a
recessed latching portion 94. The guiding slot 92 cooperates with
the keying and guiding features 58 and 60 to guide the ink
container 12 into the ink container receiving station 88. The
keying and guiding slot 92 associated with the corresponding keying
and guiding feature 60 is shown in FIG. 5 and the keying and
guiding slot associated with the corresponding keying and guiding
feature 58 on the ink container 12 is not shown. The latching
features 94 are configured for engaging the corresponding latching
features 62 on the ink container 12.
[0066] shows a cross-section of a single ink container receiving
slot within the ink container receiving station 88. The ink
container receiving slot includes interconnect portions for
interconnecting with the ink container 12. In the preferred
embodiment these interconnect portions include a fluid inlet 98,
and air outlet 96 and an electrical interconnect portion 00. Each
of the interconnects 96, 98, and 00 are positioned on a floating
interconnect portion 02 which is biased along the Z-axis toward the
installed ink container 12.
[0067] The fluid inlet 98 and the air outlet 96 associated with the
ink container receiving station 88 are configured for connection
with the corresponding fluid outlet 30 and air inlet 28,
respectively on the ink container 12. The electrical interconnect
00 is configured for engaging the plurality of electrical contact
54 on the ink container 12.
[0068] shows a large format printer 10 of the type which includes a
transversely movable printhead carriage enclosed by a plastic or
metal hinged cover 12 which extends over a generally horizontally
extending platen 14 over which printed media is discharged. At the
left side of the platen is a transparent hinged cover 16 which
contains four removable ink reservoirs 20, 22, 24, 26 which,
through a removable flexible tube arrangement to be described,
supply ink to four inkjet printheads mounted on the moveable
carriage.
[0069] In the plan view of FIG. which the carriage cover 12 has
been removed, it is seen that the printhead carriage 30 is mounted
on a pair of transversely extending slider rods or guides 32, 34
which in turn are rigidly affixed to the frame of the printer. Also
rigidly affixed to the frame of the printer are a pair of tube
guide support bridges 40, 42 from which front and rear tube guides
44, 46 are suspended. The printhead carriage 30 has a pivotal
printhead holddown cover 36 fastened by a latch 38 at the front
side of the printer which securely holds four inkjet printheads,
one of which is shown in FIG. 7 in place in stalls C, M, Y, B on
the carriage. The front tube guide 44 is angled near the left
bridge support 40 to provide clearance for opening the printhead
cover when the carriage is slid to a position proximate the left
side of the platen 14 so that the printhead holddown cover 36 can
be easily opened for changing the printheads.
[0070] A replaceable ink delivery tube system described in more
detail below conveys ink from the four separate ink reservoirs 20,
22, 24, 26 at the left side of the printer through four flexible
ink tubes 50, 52, 54, 56 which extend from an ink reservoir
connector 70 through the rear and front tube guides 44, 46 to a
printhead connector 100 which is releasably affixed to the carriage
30.
[0071] At the right side of the printer is a printhead service
station 80 at which the printhead carriage 30 may be parked for
servicing such as wiping, spitting or priming the printheads.
[0072] As seen in FIG. each of the four ink reservoirs 20, 22, 24,
26 is easily accessible from the front of the printer when the
cover 16 (seen in FIG. 1) is open so that the reservoirs can be
easily removed or replaced with new reservoirs. As is known in the
art, three of the reservoirs each contain a different base color of
ink such as cyan, magenta and yellow and the fourth reservoir
contains black ink so that a high number of colors can be produced
as desired during printing. FIG. 11 shows an ink connector 23, an
air connector 25 and an electrical connector 27 on the front end of
an ink reservoir 20. The other reservoirs are similarly
constructed.
[0073] The replaceable ink delivery tube system is broadly
comprised of the four flexible ink delivery tubes 50, 52, 54, 56
which are all permanently connected at one end to the printhead
connector 100 which is a relatively rigid plastic part best seen in
FIGS. and, at the other end, to the reservoir connector 70 which is
another relatively rigid plastic part best seen in FIGS. 9 and
12-15.
[0074] Referring now to FIGS. 7 and 8, four printheads 140 (one of
which is shown in phantom in FIG. 7 are received in the four
separate stalls C, M, Y, B on the carriage 30 and have ink
reception ports which respectively mate with ink delivery
connectors 110, 112, 114, 116 on the printhead connector 100. Each
stall has a different printhead lockout configuration comprised of
various vertically extending lockout posts 120-125 formed on the
printhead connector 100 in different positions around the ink
delivery connector ends 110, 112, 114, 116 so that each stall is
different and can only be mated with a printhead 140 of
complementary configuration. By way of illustration only, the left
stall C is configured to receive a printhead containing cyan
colored ink. The adjacent stall M is configured to receive magenta,
the next stall Y to the right is configured to receive yellow ink
and the stall B at the right side of the connector 100 is
configured to receive a printhead containing black ink.
[0075] FIG. 8 shows a printhead 140 configured to be received in
the cyan stall of the printhead connector 100. The printhead 140
includes two rows downwardly directed inkjet nozzle 142 and a
pivotally mounted handle 144 at the top for removing the printhead
104 from the carriage 30. The cyan ink delivery connector 110 on
the printhead connector is received in a generally vertically
extending ink receiving tube 146 on the cyan printhead. Proximate
the lower end of the ink receiving tube 146 is a lockout collar 148
integrally formed with the printhead 140 with a portion shown in
phantom which has been broken off or otherwise removed at the
factory so that the cyan configured printhead 140 can only be
receivable in the cyan stall C of the printhead connector 100 to
properly connect the ink delivery connector end 116 tube with the
cyan printhead 140. It will be appreciated that printheads may be
mass produced with frangible collars 148 extending generally all
the way around the ink receiving tube 146 and that selected
portions of the collars 148 can be easily removed at the factory to
thus create cyan, magenta, yellow and black printheads each having
different configurations which are uniquely receivable only in the
appropriate stalls of the printhead connector 100. The partially
removable or frangible collars 148 may be removed at selected
locations whereby the remaining portions of the collars 148 are
receivable only in the mating stalls on the printhead connector.
Alternatively, it will be appreciated that the printhead connector
lockout posts 120, 125 may be constructed so that they are easily
broken off or otherwise removed in selected areas for mating with
appropriately configured printheads.
[0076] The replaceable ink delivery tube system of the present
invention comprised of the flexible ink delivery tubes 50-56 and
printhead connector 100 is completed by the ink reservoir connector
70 (FIGS. 9 and 12-15) which is permanently affixed to an ink
supply end of the ink delivery tubes. The reservoir connector
comprises a plastic frame 72 having guide channels 73 which mate
with guide rails on the printer frame and a vertically extending
flange 74 to which a printed circuit board PCB, not part of the
present invention, is rigidly attached. The frame 72 includes a
pair of vertically extending sides 76, 78 and defines four parallel
connector module stalls separated by vertically extending divider
walls 80, 82, 84. The frame is open at the front and rear sides so
that the ink delivery ends of ink reservoirs 20, 22, 24, 26 may be
received in the stalls from the front side of the printer. The
front side of the reservoir connector 70 seen in FIG. 9 and shows
modules, described below, having ink delivery inlets 50i, 52i, 54i,
56i, air connections 90, 91, 92, 93 and electrical connectors 94,
95, 96, 97 which mate with like connections on the reservoirs, the
modules being mounted in the module stalls and extending through
the stalls in the frame 72 to the rear side of the printer.
[0077] Four reservoir connector modules 200, 202, 204, 206 are
resiliently mounted in each of the four stalls of the frame 72 such
that the four modules are forwardly and rearwardly moveable with
respect to the frame and slightly laterally moveable with respect
to the frame under the influence of a pair of compression springs
208, 210 extending between each module and spring seats on the
frame 72 to permit the modules to readily connect to and disconnect
from the ink reservoirs 20, 22, 24, 26 which are manually inserted
from the front of the printer. Each module ink port 90, 91, 92, 93
receives ink from one ink reservoir 20, 22, 24, 26, and the air
connections 90, 91, 92, 93 deliver compressed air to the
reservoirs.
[0078] The rear side of the reservoir connector 70 as seen in FIG.
12, includes a pair of quick release twist connectors 212, 214
which are easily gripped between the thumb and fore finger which
can be rotated as desired to rotate locking shafts received in
apertures in the printer frame to connect and disconnect the
reservoir connector 70 from the printer frame. An air delivery
manifold 216 is mounted on the rear of the upwardly extending
flange 74 and includes a quick release connector for connecting and
disconnecting the manifold 216 to a flexible air supply line which
delivers air through four tubes 218, 220, 222, 224 to the modules
200, 202, 204, 206 to pressurize each of the four ink reservoirs
when connected to the modules to cause the ink reservoirs to
deliver ink under pressure through the ink delivery connections
50i, 52i, 54i, 56i and the four ink supply tubes 50, 52, 54, 56
which are respectively connected to ink supply outlets 50o, 52o,
54o, 56o on the rear side of the modules. Also shown is a a main
electrical connector 230 extending through an aperture 232 in the
flange 74 which connects to the circuit board and four electrical
connections 234, 236, 238, 240 of conductors 248, 246, 244, 242
extending from the circuit board through the frame 72 to the
connectors 94-97 on the front of the modules. Disconnection of the
main air supply line from the manifold 216 and disconnection of an
electrical conductor strip from the main electrical connector 230
is quickly made by from the rear side of the printer so that the
entire reservoir connector including the permanently connected ink
delivery tubes 50, 52, 54, 56 can be removed from the printer
merely by rotating the quick release connectors 212, 214. A rigid
plastic tube clip 250 having a bayonet connector 252 which is
readily slidably received in and removed from an aperture in the
printer frame is also provided to hold the ink delivery tubes 50,
52, 54, 56 in the proper spaced relationship to each other
proximate the reservoir connector 70.
[0079] Ink reservoir lockouts 270 are provided to ensure that ink
reservoirs are containing only one type of ink, for example pigment
based ink, can be received in the reservoir connector. In the
preferred embodiment, these lockouts take the form of four separate
removable members 270 slideably received in slots 272 in the top
portion of the frame 72 above the four modules. In the
configuration shown, each lockout 270 has three horizontally spaced
downwardly extending fins 274, 276, 278 which mate with ink
reservoirs having four horizontally spaced upwardly extending fins
280, 282, 284, 286 (FIG. 11) to ensure that reservoirs containing
one type (not color) of ink only, e.g. pigment based ink rather
than dye based ink, can be received in the frame 72. Separate
lockouts (not part of this invention) are also provided near the
front end of the reservoir stalls in the printer frame to ensure
that reservoirs containing only the appropriate color of ink may be
received in the four reservoir stalls. As seen in FIG. 9 one of the
lockouts 270 has been removed to more clearly show the slots 272 in
the frame in which the lockouts 270 are slideably received. Also
note in FIG. 9 that the lockouts 270 each have vertically
upstanding bosses 288 integrally formed thereon which, when the
lockouts 270 are fully inserted into the slots 272 in the frame 72,
provide an additional means of affixing the printed circuit board
to the front of the upstanding flange 74 at the top of the
reservoir connector frame.
[0080] It is thus seen that an easily replaceable ink delivery tube
system has been provided which is uniquely useable with ink of a
selected type, e.g. pigment based ink or dye based ink but not
both, due to the lockouts 270 provided at the ink reservoir
connector 70 and which is uniquely connectable to printheads of a
selected color due to the lockout collars 148 on the printheads and
the lockout posts 120-125 provided on the printhead connector 100.
Removal of the entire system from the printer when it is desired to
change from, e.g. pigment based ink to dye based ink, prevents
fouling of the ink delivery system in a foolproof manner by
inadvertent use of ink of the wrong type therein. The replaceable
delivery system is easily removed from the printer merely by
disconnecting the air line and electrical connections at the
reservoir connector 70 so that the reservoir connector can be
removed from the printer, by removing the printheads from the
carriage and then disconnecting the printhead connector 100 from
the carriage 30 merely by squeezing the resilient finger tabs 102,
104 while pulling the printhead connector 100 from under the
carriage 30 and by removing the ink delivery tube clip from the
rear tube guide 46.
[0081] It will be understood by those skilled in the art that the
invention provides an integrated, modular and easily configurable
flexible system to pressurize ink in order to deliver it to inkjet
printheads at the required flow rate and pressure. This is
especially relevant for the ink supply system of so-called
regulator printheads that require continuous refilling.
[0082] The air pressure system (APS) provides and controls the
pressurization of the ink in the ink cartridges during a printing
operation. This ensures that the ink supplied to the inlet to the
printhead is at the correct minimum pressure to ensure correct
printhead function. The internal pressure in the printhead should
remain within necessary limits for the desired print quality at
various respective print speeds. Pressurization is particularly
useful for a system where the ink supply is remote from the
printhead such as off the carriage, in order to overcome pressure
losses with long connecting tubes and to allow machine design
flexibility for ink cartridge location and especially ink cartridge
height, as well as tube diameters, fluid interconnects, etc.
[0083] The following components are particularly helpful in
providing an inter-related system of air pressure monitoring and
control. The air pump reliably pressurizes the air and thereby the
ink to the required pressure in the required time. The pressure
sensor provides measurement of the air pressure for its feedback
control. The solenoid pressure valve enables rapid depressurization
of the system. The mounting base locates the pump, sensor and
pressure valve with associated tubing manifold, quick connect,
while also providing a sump to contain possible ink leakage from
the valve due to any ink leakage in the cartridge contaminating the
air circuit.
[0084] The flexible tubing enables easy connection of the
distributed parts of the pressure system. The various manifolds
provide secure interconnection of the multiple air tubes forming
the air circuit. The outer sheet of the ink cartridges effectively
forms part of the air circuit, and the flexible ink bag isolates
the ink from the air whilst allowing pressure transmission. The
small air leak vent allows pressure equalization with the
atmosphere when not printing. The restraint frame around the member
holding the ink cartridges helps to resist the forces developed by
the high pressure in the ink cartridges. The quick connections for
the air tubes facilitates the quick coupling for the two halves of
the air circuit and also results in easy replacement of certain
portions of the air tubes.
[0085] It is important to note that the modular system allows for
ease of modification or expansion. The programmable firmware which
controls the ink pressure levels allows easy adjustment to suit
individual product, printhead and ink needs. Such flexibility is
enhanced by the use of an analog pressure sensor to control an
oversized air pump. Also, all electro-mechanical components can be
housed in the electronics shielding enclosure with the pneumatic
power connection to the ink cartridges only by air, thus
eliminating completely all electrical emission problems.
[0086] The pressure relief valve is normally closed. This means
that the valve is closed when no voltage is applied, so that the
air system circuit is fail-safe--it is closed when the machine is
turned off, or in reshipping, or between plots. The valve is the
only possible opining for ink of the air circuit/secondary
containment when the ink cartridges are fitted in the plotter.
[0087] Each ink cartridge has its only slow leak vent with built-in
filter that does not allow ink to pass. For the printer system this
provides the means to avoid the system pressurizing itself with
temperature or altitude changes in shipping or storage. This is
also particularly useful for shipment of the individual ink
cartridges separate from the printer.
[0088] The air tubing is raised above the maximum ink level in the
cartridges. This is to provide a simple gravity check against any
ink leak in a cartridge entering the air circuit. Moreover each
cartridge has a pair of exposed contacts on the outside of the ink
bag to detect ink by change in resistance. The printer checks these
on machine switch on and before pressurisation for any plot. If any
leak is deteted the system will not pressurise and will notify the
user to change that ink cartridge. This is to preven any ink
getting into the air system at all. Also, at the outlet of the
pressure relief valve is a sump to catch ink ejected from a
contaminated air system. There there are three levels of ink
containment which reduces the probability of ink ever being leaked
onto a customer's carpet or floor.
[0089] As shown in the flow chart of the drawings, there is a
specific sequence of steps which assures that the minimum ink
pressure is reached quickly before the printing operation begins.
The actual air pressure required is determined at the start of each
plot dependent on the volume of ink left in the cartridge since a
major pressure loss contributor is the ink bag when nearly empty,
and which color, since the color masimum flow rate is lower. The
pressure is maintained for a predetermined wiat time between plots,
thus giving effectively no warm up time for the air pressure system
for high throughput printing.
[0090] The housing supports the ink cartridge sides by providing
spacers between the cartridges and a structural reinforcing loop of
metal around the outside of the entire cartridge group. The housing
provides the base which together with a sheet metal frame clipped
in from the top completes the closed loop. This allows the
cartridge bottle to be blow moulded for low cost using generally
low rigidity materials, thereby also achieveing the industrial
design needs for a book-shaped form factor.
[0091] The following tables provide various data and operating
ranges for the air pressure system:
1 Preferred Default Parameters For Air Pressurization System (APS)
Parameter Name Value Unit Print pressure Pnormal 1.2 psi normal
Print pressure Pblack 1.85 psi Black <80 cc absolute Print
pressure Pcolour 1.4 psi Colour <80 cc absolute Stop pressure
Pstop 2.25 psi Repump pressure Prepump 1.95 psi Pump pressure rate
Rpump 0.2 psi/s Print pressure wait Tcheck 0.15 s time for fine
checking Minium pump on time Tmin 0.1 s to reach print pressure
Post plot wait time with Twait 5 minutes pressure maintained
Pressure sensor maximum offset Pcal +0.25 psi calibration allowed
-0.25 Maximum time to Pprint 20 s in first (coarse) check Maximum
time to Pprint 10 s in fine check Min pressure allowed at start of
Pprint psi swath (except first) during printing Depressurization
check Max Tdep 0.3 psi pressure after valve open 20 s Valve open
time for Tvalve 30 s depressurization Pnormal: All cartridges
operating in "normal" pressure loss range. Pcolor: Any color
cartridge in "nearly empty" range, black in normal range. Pblack:
Black in nearly empty range.
[0092] Pressure Budget
[0093] The required minimum air pressure at flow Q is given by:
P(air)=Pat Q)+P(head loss)+P(flow losses at Q)+Pbag
[0094] Where:
[0095] P(air): The pressure measured by the sensor: effectively
equal to the pressure in the
[0096] P( The minimum inlet pressure defined by at specified pen
flow rate.
[0097] P(head): Pressure loss due to the height difference between
the inlet and the exit.
[0098] P(flow): Pressure loss due to flow friction at specified
flow rate.
[0099] P Pressure loss due to bag collapse resistance
2TABLE Key Parameters Platform maximum flow rate 24 cc/min
Printhead platform black pen max flow rate 20 cc/min Printhead
platform color pens max flow rate 6 cc/min Printhead platform min
pressure.sup.1 to ensure PQ: Q (cc/min)/2 psi 0 to 20 cc/min 10 psi
20 to 24 cc/min min pressure.sup.1 no damage: 0 psi 0 to 24 cc/min
inks max viscosity (max) 5 Centipoise . . . platform inks Inkbag
pressure loss.sup.2 (max) 0.15 psi Full to 80 cc (abs) ink
remaining 0.69 psi 80 cc to empty (99%) 1.05 psi 80 cc to empty
(3.sigma.) Printhead inlet height above ink 137 mm Small bag (350
& 175 cc) bag outlet height 161 mm Large bag (700 cc) Pressure
measurement error (max) 0.15 psi Sensor & electronics errors
After zero offset calibration .sup.1Defined at the inlet holes in
the pen needle. .sup.2Defined at the centre of the ink outlet
septum.
[0100] The time to presssure is directly proportional to the air
volume to be compressed, and thus depends on the cartridge size and
the ink remainin in each.
[0101] The following duty cycle description explains the duty cycle
curve shown in the drawings:
[0102] The APS Duty Cycle
[0103] A) System de-pressurized: pump off, valve closed. Air
pressure equalisation through the Mirage vents.
[0104] B) Incoming plot detected: pump on full speed to Pblack,
printing allowed as soon as Pprint reached.
[0105] C) Pblack to Pstop pump runs at half speed and stops at
Pstop.
[0106] D) Pressure decays to Prepump at rate dependent on system
air volume, Mirage vent leaks, system leakage, and ink use
rate.
[0107] E) At Prepump pump on until Pstop reached.
[0108] F) Repeat of (D) to (F) until plot finished.
[0109] G) APS maintains (D) to (F) loop for Twait, unless plot
received.
[0110] H) Valve opened for Tvalve to de-pressurize system.
[0111] Time to Pressure
[0112] This is important for the time to reach print pressure only,
since after this point the APS works in the background maintaining
the ink pressure. This APS "warm up time" runs in parallel with the
time used for servicing at the start of any plot when the APS is
de-pressurized: whichever is the longer defines the delay between
plot detection and print start (assuming plot processing time is
less).
3TABLE Time to Pressure Key Parameters RR warm up delay from "cold"
5 seconds To meet RR throughput goals. Time to print pressure 5
seconds Goal for pump selection for for 4 empty 350 cc Mirage
Roadrunner. to Pnormal Air volume range: min: 395 cc Includes 17 cc
RR air circuit 350 cc Mirage max: 1985 cc 700 cc Mirage max: 3680
cc Wait time pressurized 5 (tbc) minutes To be optimised for Use
Model.
[0113] Air Leakage
[0114] The total APS air leak rate is an important system variable
for pump life and duty cycle, and for pressure checking frequency.
In the APS design, the leak rates are defined as a flow rate at a
pressure; the flow rate is always defined in terms of standard air
(air at 14.7 psi absolute and 60.degree. F.).
[0115] The system's dominant source of leakage is the designed-in
leakage of the four cartridges, followed by the pump, with the
valve having at least an order of magnitude lower leakage. The rest
of the air circuit is airtight.
[0116] The effect of leakage on the pump life requirement is also
dominant: more than a minimum of 50% of the air pumped is expected
to be used to replace leaked air. Air vented to atmosphere each
time the system de-pressurizes is the next major contributor. While
the air actually used to replace the ink used is two orders of
magnitude lower. The pump duty cycle is directly affected by the
leakage, but the system air volume range is also significant in
defining pump off time.
[0117] Note that the vent is fitted in the cartridge to equalise
pressure (and thus avoid creep of its shell) during transport. The
APS uses this feature to allow pressure equalisation of the printer
when de-pressurized, as the air circuit (in particular the relief
valve) is normally closed.
[0118] Air Pump
[0119] This is a triple cylinder diaphragm pump using a swashplate
mechanism driven by a DC motor. This provides a compact and quiet
air compressor that allows speed control. The pump is used without
an air filter on the inlet. The multiple cylinder configuration
provides several important benefits of:
[0120] Low pumping noise and vibration.
[0121] Lowered pressure pulses in the air circuit (this affects
pressure measurement algorithm).
[0122] Increased reliability due to parallel system redundancy.
[0123] The swashplate mechanism is extremely compact compared to
the crank slider mechanism more commonly used in diaphragm air
pumps.
4TABLE APS Pump Requirements Time to Pressure 2.5 seconds maximum
Affects pressurization system "warm up Over Life to 2.5 psi time"
before printing can start. for 500 cc rigid volume with 24 V
nominal Supply voltage. Leak rate: Life start: 1 scc/min.sup.1
maximum Affects: system air use Life end: 10 scc/min maximum at 2.5
psi Life 50,000 standard minimum liters.sup.2 MVBF (mean volume
600,000 standard minimum During normal lifetime. between failures)
liters To meet 1% AFR budget. Duty cycle for Life and MVBF Pressure
capability 3.5 psi minimum 1 psi margin for platform future needs.
15 psi maximum To avoid safety risks. Restart pressure 3 psi
minimum To suit APS half speed repumping. at 12 V 1 psi margin for
platform future needs. Operating voltage 24 V .+-.10% supply. 0 to
100 pwm For speed control. .sup.1SCC = cc of `standard air`: air at
standard atmospheric pressure and temperature. .sup.2liters of
"standard air": air at standard atmospheric pressure and
temperature
[0124] Device selection notes: The APS design allows for relatively
easy substitution of alternative pumps: since the mechanical
functional connection to the APS is by air tube. In particular the
use of alternative motors has been foreseen in the design of the
pump mounting.
[0125] Pressure Relief Valve
[0126] This is a solenoid operated 2 way NC valve. Normally Closed
means that the valve is closed when no actuating voltage applied.
The valve has one port connected to the air circuit in the APS
module; the exit port discharges into the ink sump. No air
filtration is provided: hence, the air circuit cleanliness is
important.
5TABLE APS Pressure Relief Valve Requirements Leak rate: over Life
0.2 scc/min maximum Affects system air use Operating voltage 24 V
.+-.xx Flow xx cc/min .+-.xx Affects de-pressurization time and ink
leak at 2.5 psi detection algorithm. Life 100,000 cycles minimum
open/close MCBF (mean cycles 3,000,000 cycles minimum During normal
lifetime between failures) To meet 0.1% APR budget. Duty cycle 30 s
ON (open) for Life and MCBF 5 minutes OFF Device selection notes:
The APS design allows for the easy substitution of alternative
valves: since the functional mechanical connection to the system is
by flexible tube, and there is space to add alternative mounting
clips (indeed a redundant clip to suit standard ISO size is already
built in the support).
[0127] Pressure Sensor
[0128] This is a silicon piezoresistive device with integrated
temperature compensation and signal conditioning (amplification).
The sensor measures gauge pressure and hence has a single pressure
port that is connected to the air circuit in the APS module.
6TABLE APS Pressure Sensor Requirements Pressure range 0 to 3.5 psi
Accuracy .+-.0.1 psi Maximum pressure 15 psi No damage Equal to
pump max possible pressure Supply voltage 5 V Device selection
notes: Space is provided in the APS support for mountings for
alternative sensors.
[0129] Referring to FIGS. 16-17, an air system support frame 700
carries an air pump 702, a pressure sensor 704, and a pressure
relief valve 706 which all connect through adaptor 708 to flexible
conduit 710 having a locking connector 712 for attachment to the
manifold on the back of the ink connector member. The frame is in a
modified cup shape to create a sump 714 under the pressure relief
valve for collecting any ink which may leak from the ink container
through the air lines. These air system components each have
electrical power supply lines, with a three-wire line 716 connected
to the pressure sensor for transmission of data to the control
electronics. The frame 700 includes hooks 715 and tabs 717 for
mounting under the connector module at its front end as shown by
dotted lines 719.
[0130] The self-explanatory flow charts of FIGS. 18A-18D when
combined with the data and information of the various previous
tables show the sophisticated monitoring and control procedures
which can be customized by merely changing firmware without having
to change individual physical components in the system. Various
protective steps assure that any malfunction in the system will be
detected and appropriate error signals generated to alert a user
and where necessary stop and/or close down the system until a
problem is resolved.
[0131] Additional flexibility is provided for different lengths
(volumes) of ink containers as shown in FIG. 20. When a smaller
container 720 is used, a slot 722 is engaged by the fastener to
lock the connector module in a shortened position (See FIG. 5B).
When a larger container 724 is used, another slot 726 is engaged
the the fastener to lock the connector module in a lengthened
position.
[0132] Sturdy and leak-resistant construction for the ink
connection is assured by a unique tower/humidor combination shown
in FIG. 22. The humidor 728 includes opposing raised fins 730 which
initially slide down matching grooves 732 in a tower 734 until they
reach matching slots 736 which cause the humidor to slightly rotate
so that triangular fin 738 engages a matchin elongated notch 740
thereby holding the humidor in position against a biasing spring
742. The humidor itself covers needle 744 and its ink passage 746
until compressed by a septum of an ink supply container to expose
the ink passage. A facing of different concentric layers 748 abuts
the septum to help prevent ink leakage.
[0133] Additional structural support for the ink containers when
mounted and subjected to the rising air pressures in the containe
is provided by a sheet metal loop 750 (See FIG. 5A).
[0134] It will be appreciated that the latest embodiment of the air
pressure system and related components provides very predictable
and secure control of the ink pressure whether applied to normal
printing operations, or to unusual events such as priming, air
purging of the ink tubes and the like as shown in the table of FIG.
23.
[0135] Various changes and improvements can be made to the
illustrated embodiments disclosed herein without departing from the
spirit and scope of the invention as set forth in the following
claims.
* * * * *